do I really need yet another version of the bratty jerky genius manchild and his devoted wrangler?

This was my question, too, especially in making Watson female and Asian, both groups that get stereotyped as subservient helpers. Instead, they've completely turned it around and made them very much equals. One thing I like about the ACD canon which adaptions don't often preserve is the way that Watson has his own life quite apart from Holmes, but it's definitely true here. Plus, neither Watson nor the audience had to worship everything Holmes did, AND he was sympathetic to the abused mentally ill character and outraged at his treatment. I was surprised and thrilled.